1. Technical Field
The present disclosure relates to methods for making carbon nanotube wire structure.
2. Discussion of Related Art
Carbon nanotubes can be composed of a plurality of coaxial cylinders of graphite sheets. Carbon nanotubes have received a great deal of interest since the early 1990s. Carbon nanotubes have interesting and potentially useful electrical and mechanical properties. Due to these and other properties, carbon nanotubes have become a significant focus of research and development for use in electron emitting devices, sensors, transistors, and other devices.
Generally, carbon nanotubes prepared by conventional methods are in particle or powder form. The particle or powder-shaped carbon nanotubes limit the applications of the carbon nanotubes. Thus, preparation of macro-scale carbon nanotube structures has attracted attention.
A carbon nanotube wire structure is one macro-scale carbon nanotube structure. The carbon nanotube wire structure includes a number of carbon nanotubes, and qualifies as a novel potential material which can replace carbon nanofibers, graphite nanofibers, and fiberglass. The carbon nanotube wire structure is used in electromagnetic shield cables, printed circuit boards, special defend garments, and so on.
A typical example is shown and discussed in U.S. Publication. No. 20070166223A, entitled, “METHOD FOR MAKING CARBON NANOTUBE YARN,” published to Fan et al. on Jul. 19, 2007. This patent discloses a carbon nanotube yarn. The method for making the yarn includes providing a super-aligned carbon nanotube array; drawing a carbon nanotube film from the carbon nanotube array; treating the carbon nanotube film with an organic solvent to form a carbon nanotube yarn.
However, a diameter of the yarn made by the method is restricted by a scale of the carbon nanotube array. The carbon nanotube array is usually grown on a silicon substrate. A large silicon substrate is difficult to produce using the present silicon technology. Therefore, it is difficult to acquire a large area of the carbon nanotube array. Thus, the yarn twisted by the pre-primary assembly has a small diameter and the mechanical strength and toughness of the yarn is inferior, thereby limiting its application.
What is needed, therefore, is a method for making a carbon nanotube wire structure with a large diameter, superior mechanical strength, and superior toughness.